Objective: Autism is a developmental disorder defined by impaired social interaction, communication, and behavior. Causes and correlates of autism are largely unknown, but elevated frequencies of psychiatric disorders and distinct personality traits have been reported among the family members of individuals with autism. Linkage of data from Swedish registries was used to investigate whether hospitalization for psychiatric conditions was higher among parents of children with autism compared with control subjects.
Methods: Data sources included the Swedish Medical Birth Register (child's birth), the Swedish Multi-Generation Register (linking parents to children), and Swedish Hospital Discharge Register (hospitalization records). Children born between 1977 and 2003 who had a hospitalization record indicating autism before 10 years of age (n = 1227) were matched with 30,693 control subjects from the Swedish Medical Birth Register by gender, year of birth, and hospital. Parent diagnoses were based on an inpatient hospital diagnostic evaluation and included schizophrenia, other nonaffective psychoses, affective disorders, neurotic and personality disorders and other nonpsychotic disorders, alcohol and drug addiction and abuse, and autism. Odds ratios and 95% confidence intervals were estimated by using conditional logistic regression, adjusted for child's age, gender, hospital of birth, parents' age, country of birth and socioeconomic status, and diagnosis of a mental disorder in the other parent.
Results: Parents of children with autism were more likely to have been hospitalized for a mental disorder than parents of control subjects. Schizophrenia was more common among case mothers and fathers compared with respective control parents. Depression and personality disorders were more common among case mothers but not fathers. CONCLUSIONS; This large population study supports the potential for familial aggregation of psychiatric conditions that may provide leads for future investigations of heritable forms of autism.